Method for preparing lithium manganate after EMD modification and impurity reduction

Abstract

The invention provides a method for preparing lithium manganate after EMD modification and impurity reduction, and belongs to the technical field of energy materials. Comprising the following steps: carrying out pretreatment to obtain EMD fine powder, sintering the EMD fine powder into manganese sesquioxide, cooling, washing and drying to obtain impurity-reduced manganese sesquioxide, and mixing and sintering the impurity-reduced manganese sesquioxide, a lithium salt and a metal oxide to obtain lithium manganate. After EMD electrolysis, residual electrolyte on the surface is washed away, then the powder is smashed into fine powder, and finally the content of sulfate radicals and various metal cations such as potassium, sodium, calcium and magnesium can be greatly reduced through calcination and rinsing. Manganese sesquioxide obtained by treating EMD through the method is low in impurity content, crystals are of an octahedral structure, spinel type lithium manganate is easier to fire compared with EMD, and the electrical performance of the lithium manganate positive electrode material prepared under the same technological formula is far better than that of lithium manganate prepared through traditional EMD.

Description

Technical Field

[0001] This application belongs to the technical field of energy materials, and particularly relates to a method for preparing lithium manganate after EMD modification and impurity reduction. Background Art

[0002] Spinel lithium manganate (LiMn 2 O 4 ) cathode material is an ideal power battery material due to its advantages such as rich manganese resources, pollution-free, good safety performance and rate performance, and low manufacturing cost. As is well known, the preparation method of the cathode material and the properties of the raw materials have a great influence on the physical and electrochemical properties of the product. At present, manganese sources that can be used as spinel lithium manganate include MnO 2 , Mn 3 O 4 , Mn 2 O 3 and other manganese compounds. The mainstream manganese sources for industrial production of spinel lithium manganate at home and abroad are electrolytic manganese dioxide (EMD) and Mn 3 O 4 . Compared with Mn 3 O 4 , sintering EMD to prepare lithium manganate has advantages such as good processing performance and high compaction, but at the same time, it also has disadvantages such as many impurities and low content, which affect the electrochemical performance of lithium manganate. The main impurities in EMD are sulfate (SO 4 2- ) > 1% and sodium > 2500 ppm. Sulfate cannot be decomposed during the sintering process of lithium manganate, and sodium will enter lithium manganate and occupy part of the lithium position. On the one hand, it destroys the original spinel structure stability and affects the electrochemical performance of lithium manganate. On the other hand, the presence of sodium also affects the diffusion path and rate of lithium ions, thereby affecting the charge and discharge efficiency and power output of the battery. Summary of the Invention

[0003] This application provides a method for preparing lithium manganate after EMD modification and impurity reduction, aiming to solve to a certain extent the problem that excessive impurities in EMD cannot be decomposed during the sintering process of lithium manganate, thus affecting the electrochemical performance of lithium manganate.

[0004] In the first aspect, this application provides a preparation method for preparing lithium manganate after EMD modification and impurity reduction, including the following steps: S1, Pretreatment: Wash the EMD semi-finished product with hot water to remove acid, grind it after drying, and classify and powder it to obtain EMD fine powder; S2, Firing: Burn the EMD fine powder into manganese dioxide, wash and dry it after cooling to obtain impurity-reduced manganese dioxide; S3, Preparation: Mix and sinter the EMD fine powder, the impurity-reduced manganese dioxide, lithium salt and metal oxide to prepare lithium manganate.

[0005] In one embodiment, the process conditions of the hot water acid washing in S1 are as follows: the temperature is 60°C - 100°C, the washing time is 20 min - 1 h, and the cyclic washing is carried out 2 - 3 times. The grinding in S1 is ball milling, and the particle size distribution requirements of the EMD fine powder are as follows: D10 = 1.5 - 5 μm, D50 = 8 - 15 μm, D90 = 20 - 35 μm.

[0006] In one embodiment, the process conditions of the firing into manganese dioxide in S2 are as follows: firing in a roller hearth kiln, the calcination temperature is 600°C - 900°C, and the calcination duration is 2 h - 6 h.

[0007] In one embodiment, the process conditions of the washing in S2 are as follows: washing with pure water according to a solid - liquid ratio of 1∶2 - 4 for 2 - 5 times, and the washing time is 20 min - 1 h.

[0008] In one embodiment, the content of each impurity metal ion in the impurity - reduced manganese dioxide in S2 is less than 100 ppm, the content of impurity sulfate radical is less than 0.6%, and the specific surface area of the impurity - reduced manganese dioxide is 0.5 m 2 / g - 1.5 m 2 / g.

[0009] In one embodiment, the impurity metal ions include at least one of potassium, sodium, calcium, and magnesium.

[0010] In one embodiment, the lithium salt in S3 is one or a combination of lithium carbonate and lithium hydroxide.

[0011] In one embodiment, the metal oxide in S3 is Al 2 O 3 、TiO 2 、MgO、La 2 O 3 、ZrO 2 or a combination of one or more of them.

[0012] In one embodiment, the molar ratio of Mn∶Li atoms in the EMD fine powder, the impurity - reduced manganese dioxide, and the lithium salt in S3 is (1.6 - 2)∶1; the addition amount of the metal oxide is 0.1% - 1% of the total mass of the manganese source and the lithium salt.

[0013] Compared with the prior art, the beneficial effects of this application are as follows: 1. Before calcining EMD, the present invention first grinds and powders it. Since the EMD electrolytic deposition process takes a long time, EMD is soaked in the electrolyte for a long time, and the generated EMD has a porous structure and will adsorb impurities. The newly generated EMD will also be wrapped. Therefore, there are many impurities adsorbed and wrapped inside the EMD. The EMD is crushed to a particle size of D50 = 8 - 15 μm. The smaller the particles, the more impurities are exposed inside the EMD, and the more impurities can be removed by washing after sintering.

[0014] 2. After the EMD is electrolyzed in the process of the present invention, only acid washing is required without neutralization, and then through calcination and rinsing, the contents of sulfate radicals and various metal cations such as potassium, sodium, calcium, and magnesium can be greatly reduced.

[0015] 3. The manganese dioxide obtained by calcining and rinsing EMD in the present invention has a low impurity content. The contents of potassium, sodium, calcium, and magnesium in the obtained manganese dioxide material are all within 50 ppm. The crystal is an octahedral structure, and it is relatively easier to sinter spinel-type lithium manganate than EMD. The electrical properties of the lithium manganate cathode material prepared under the same process formula are far better than those prepared from EMD. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 、 Figure 2 SEM images of different magnifications of the EMD raw material in Example 1; Figure 3 、 Figure 4 SEM images of different magnifications of the manganese dioxide in Example 3; Figure 5 SEM results of sintering lithium manganate with manganese dioxide in Example 3 as the manganese source; Figure 6 SEM results of sintering lithium manganate with EMD in Comparative Example 3 as the manganese source. Detailed Embodiments

[0018] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application more clear, the following further details the present application in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0019] In this application, the term "and / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone. Here, A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0020] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following items" or its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a~b (i.e., a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple respectively.

[0021] The terms "first" and "second" are only used for descriptive purposes to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. For example, without departing from the scope of the embodiments of this application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Thus, the features defined with "first" and "second" can explicitly or implicitly include one or more of such features.

[0022] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a", "the", and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0023] It should be understood that in various embodiments of this application, the magnitude of the sequence numbers of each process does not mean the order of execution. Some or all of the steps can be executed in parallel or successively. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0024] The weights of the relevant components mentioned in the specification of the embodiments of this application can not only refer to the specific contents of each component, but also represent the proportional relationship of the weights between the components. Therefore, as long as the contents of the relevant components in the specification of the embodiments of this application are scaled up or down in proportion, they are within the scope disclosed in the specification of the embodiments of this application. Specifically, the mass described in the specification of the embodiments of this application can be mass units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0025] Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of the present invention.

[0026] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in this application can be obtained through the market or can be prepared by existing methods.

[0027] The technical solutions of this application will be described below through specific examples and comparative examples.

[0028] To enable those skilled in the art to clearly understand the above implementation details and operations of this application, and to significantly demonstrate the improved performance of the embodiments of this application, the above technical solutions will be illustrated by multiple examples below.

[0029] A method for preparing lithium manganate after EMD modification and impurity reduction, comprising the following steps: S1, pretreatment: hot water wash the EMD semi-finished product with acid, grind it after drying, classify and make powder to obtain EMD fine powder; S2, firing: firing the EMD fine powder into manganese dioxide, washing and drying after cooling to obtain impurity-reduced manganese dioxide; S3, preparation: mixing and sintering the EMD fine powder, the impurity-reduced manganese dioxide, lithium salt and metal oxide to prepare lithium manganate.

[0030] In one embodiment, the process conditions for the hot water wash with acid in S1 are: the temperature is 60°C - 100°C, the washing time is 20 min - 1 h, and the cyclic washing is 2 - 3 times. The grinding in S1 is ball milling, and the particle size distribution requirements for the EMD fine powder are: D10 = 1.5 - 5 μm, D50 = 8 - 15 μm, D90 = 20 - 35 μm.

[0031] In one embodiment, the process conditions for firing into manganese dioxide in S2 are: firing in a roller hearth kiln, the calcination temperature is 600°C - 900°C, and the calcination duration is 2 h - 6 h.

[0032] In one embodiment, the process conditions for the washing in S2 are: washing with pure water 2 - 5 times according to the solid-liquid ratio of 1:2 - 4, and the washing time is 20 min - 1 h.

[0033] In one embodiment, the content of each impurity metal ion in the impurity-reduced manganese dioxide in S2 is less than 100 ppm, the content of impurity sulfate radical is less than 0.6%, and the specific surface area of the impurity-reduced manganese dioxide is 0.5 m 2 / g - 1.5 m 2 / g.

[0034] In one embodiment, the impurity metal ions include at least one of potassium, sodium, calcium, and magnesium.

[0035] In one embodiment, the lithium salt in S3 is a combination of one or more of lithium carbonate and lithium hydroxide.

[0036] In one embodiment, the metal oxide in S3 is Al 2 O 3 、TiO 2 、MgO, La 2 O 3 、ZrO 2 or a combination of one or more of them.

[0037] In one embodiment, the molar ratio of Mn:Li atoms in the EMD fine powder, the manganese sesquioxide for impurity reduction, and the lithium salt in S3 is (1.6 - 2):1; the addition amount of the metal oxide is 0.1% - 1% of the total mass of the manganese source and the lithium salt.

[0038] Example 1: A preparation method of EMD-modified manganese sesquioxide for impurity reduction: Prepare a high-purity manganese sesquioxide precursor: Use the EMD semi-finished product obtained by electrolyzing the manganese sulfate solution of Xiangtan Electrochemistry Technology Co., Ltd. as the raw material. First, wash the acid of the EMD semi-finished product with hot water at a temperature of 85°C for 40 minutes, and wash it three times in a cycle. After drying, ball mill and classify the powder to obtain EMD with a D50 of 10 μm, and then calcine it in a roller hearth kiln at 850°C for 4 hours to obtain manganese sesquioxide. After cooling, rinse it twice with pure water and then dry it.

[0039] Comparative Example 1: A preparation method of EMD-modified manganese sesquioxide for impurity reduction. The difference between this comparative example and Example 1 is that the order of grinding and powder making and calcination is different. After washing the acid of the EMD semi-finished product, first calcine it, and then grind and make powder.

[0040] Prepare a high-purity manganese sesquioxide precursor: Use the EMD semi-finished product obtained by electrolyzing the manganese sulfate solution of Xiangtan Electrochemistry Technology Co., Ltd. as the raw material. First, wash the acid of the 10-mm EMD semi-finished product with hot water at a temperature of 85°C for 40 minutes, and wash it three times in a cycle. After washing the acid, the EMD is calcined in a roller hearth kiln at 850°C for 4 hours. After cooling, ball mill and classify the powder to obtain manganese sesquioxide with a D50 of 10 μm. After rinsing it twice with pure water, dry it.

[0041] For the treatment processes of the manganese sesquioxide in Example 1 and Comparative Example 1, the impurity detection results of the obtained products are shown in Table 1.

[0042]

[0043] As shown in Table 1 above, the content of each impurity in the manganese dioxide prepared by the steps of the process of Comparative Example 1, "after washing the EMD semi-finished product with acid, first calcining, then grinding and powder making", is significantly more than that of the product of Example 1. The potassium, sodium, calcium, and magnesium in the sample material obtained by the process of this example are all within 50 ppm. The mechanism is that there are a large number of pores inside the EMD product. During the electrolysis process, the EMD accumulates layer by layer on the anode plate. After some pores adsorb various impurities, they are covered and wrapped by the newly formed EMD, forming closed pores. Although the large-particle sample has deformation during the calcination process, not all closed pores can be released. Therefore, grinding into fine powder first to open some closed pores is beneficial to reducing the product impurities in the subsequent process.

[0044] Example 2: A method for preparing lithium manganese oxide after modifying and reducing impurities of EMD: S1. Using the EMD semi-finished product obtained by electrolyzing the manganese sulfate solution of Xiangtan Electrochemical Technology Co., Ltd. as the raw material, first wash 5 kg of the EMD semi-finished product with hot acid at a temperature of 65 °C for 50 min, and wash three times in a cycle. After washing with acid, dry and then carry out ball milling and classification to make powder, with particle size D10 = 2.38 μm, D50 = 9.31 μm, D90 = 24.72 μm.

[0045] S2. Calcinate the EMD powder using a roller hearth kiln at a calcination temperature of 600 °C for 6 h. After calcination, manganese dioxide is obtained. Wash the manganese dioxide twice according to a solid-liquid ratio of 1:3 and dry. The component detection results of the manganese dioxide are shown in Table 2.

[0046] S3. Weigh 2780.1 g of EMD, 600.0 g of lithium carbonate, and 19.3 g of aluminum oxide, and mix them thoroughly using an inclined mixer. Then weigh another 2388.7 g of manganese dioxide from step S2, 600.0 g of lithium carbonate, and 19.3 g of aluminum oxide, and mix them thoroughly using an inclined mixer. Then put the two mixed lithium manganese oxide raw materials into a roller hearth kiln to burn lithium manganese oxide at a heating rate of 2 °C / min and keep it warm at 750 °C for 18 h to obtain lithium manganese oxide. After the fired lithium manganese oxide is cooled, it is crushed and sieved, and a coin cell test is carried out. The results are shown in Table 3.

[0047] Comparative Example 2: A method for preparing lithium manganese oxide after modifying and reducing impurities of EMD: The difference between this comparative example and Example 2 is that the EMD fine powder is treated by conventional impurity reduction and alkali washing is carried out to remove acid again.

[0048] S1. Using the EMD semi-finished product obtained by electrolyzing the manganese sulfate solution of Xiangtan Electrochemical Technology Co., Ltd. as the raw material, first wash 5 kg of the EMD semi-finished product with hot acid at a temperature of 65 °C for 50 min, and wash it three times in a cycle. After acid washing, dry it and then grind and classify it into powder with particle sizes D10 = 2.38 μm, D50 = 9.31 μm, and D90 = 24.72 μm.

[0049] S2. Rinse the EMD fine powder with sodium hydroxide solution at a temperature of 80 °C for 4 h, and then wash it with hot alkali at a temperature of 70 °C for 2 times, 30 min each time. The component detection results of the EMD after alkali washing are shown in Table 2.

[0050] S3. Weigh 2780.1 g of EMD, 600.0 g of lithium carbonate, and 19.3 g of aluminum oxide, and mix them thoroughly with a skew mixer. Then weigh another 2388.7 g of commercially available manganese dioxide, 600.0 g of lithium carbonate, and 19.3 g of aluminum oxide, and mix them thoroughly with a skew mixer. Then put them into a roller hearth kiln to bake lithium manganate at the same time, with a heating rate of 2 °C / min and keep it at 750 °C for 18 h. After the baked lithium manganate is cooled, crush it and sieve it, and conduct a coin cell test. The results are shown in Table 3.

[0051] Example 3: A method for preparing lithium manganate after modifying and reducing impurities of EMD: The difference between this example and Example 2 lies in that the process parameters and oxides of acid washing and calcination are different.

[0052] S1. Using the EMD semi-finished product obtained by electrolyzing the manganese sulfate solution of Xiangtan Electrochemical Technology Co., Ltd. as the raw material, first wash 5 kg of the EMD semi-finished product with hot acid at a temperature of 85 °C for 60 min, and wash it three times in a cycle. After acid washing, dry it and then grind and classify it into powder with particle sizes D10 = 2.56 μm, D50 = 10.12 μm, and D90 = 27.82 μm.

[0053] S2. Calcinate the EMD fine powder in a roller hearth kiln at a calcination temperature of 800 °C for 3 h. After calcination, manganese dioxide is obtained. Wash the manganese dioxide four times with water according to the solid-liquid ratio of 1:3 and dry it. The component detection results of the manganese dioxide are shown in Table 2.

[0054] S3. Weigh 2676.1 g of EMD, 600.0 g of lithium carbonate, and 15.2 g of titanium dioxide, and mix them thoroughly with a skew mixer. Then weigh another 2293.3 g of manganese dioxide obtained in step S2, 600.0 g of lithium carbonate, and 15.2 g of titanium dioxide, and mix them thoroughly with a skew mixer. Then put them into a roller hearth kiln to bake lithium manganate at the same time, with a heating rate of 3 °C / min and keep it at 800 °C for 12 h. After the baked lithium manganate is cooled, crush it and sieve it, and conduct a coin cell test. The results are shown in Table 3.

[0055] Comparative Example 3: A method for preparing lithium manganate after impurity reduction by EMD modification: The difference between this comparative example and Example 3 is that the EMD fine powder is treated by conventional impurity reduction and alkali washing is carried out to remove acid again.

[0056] S1. Using the EMD semi-finished product obtained by electrolyzing the manganese sulfate solution of Xiangtan Electrochemical Technology Co., Ltd. as the raw material, first wash 5 kg of the EMD semi-finished product with hot water to remove acid, the temperature is 85 °C, the time is 60 min, and wash three times in a cycle. After washing the acid, dry it and then carry out ball milling and classification to make powder, with particle size D10 = 2.56 μm, D50 = 10.12 μm, D90 = 27.82 μm.

[0057] S2. Rinse the EMD fine powder with sodium hydroxide solution, the temperature is 70 °C, the time is 6 h, and then wash the alkali with hot water, the temperature is 60 °C, and rinse twice, each time for 1 h. The component detection results of the EMD treated by alkali washing are shown in Table 2.

[0058] S3. Weigh 2676.1 g of EMD, 600.0 g of lithium carbonate, and 15.2 g of titanium dioxide, and mix them thoroughly with a skew mixer. Then weigh another 2293.3 g of commercially available manganese sesquioxide, 600.0 g of lithium carbonate, and 15.2 g of titanium dioxide, and mix them thoroughly with a skew mixer. Then put them into a roller hearth kiln to bake lithium manganate at the same time, the heating rate is 3 °C / min, and keep it at 800 °C for 12 h. After the baked lithium manganate is cooled, it is crushed and sieved, and a coin cell test is carried out. The results are shown in Table 3.

[0059]

[0060]

[0061] Combining Table 2 and Table 3, it can be seen that compared with the lithium manganate fired from the direct mixture of EMD raw materials and the lithium manganate fired from the mixture of the EMD-modified manganese sesquioxide raw materials, the EMD after impurity reduction by the process of this scheme is made into manganese sesquioxide as the manganese source, and the content of various impurities is significantly reduced. The impurities potassium, sodium, calcium, and magnesium in the manganese sesquioxide sample material are all within 50 ppm. The lithium manganate fired under the same process formula has obvious improvement in both capacity and cycle performance.

[0062] As Figure 1 、 Figure 2 shown in the scanning electron microscope images of different multiples of the EMD raw material in Example 1, the EMD material is relatively compact.

[0063] Figure 3 、 Figure 4 are the scanning electron microscope images of different multiples of the manganese sesquioxide in Example 3. As shown in the figure, the crystal form changes after the EMD is fired into manganese sesquioxide, and large pores appear on the secondary particles, exposing the internal space.

[0064] As Figure 5 Figure 3 shows the SEM results of lithium manganate fired with manganese dioxide as the manganese source in Example 3. Figure 6 Figure 4 shows the SEM results of lithium manganate fired with EMD as the manganese source in Comparative Example 3. Under the same formulation, the lithium manganate fired with EMD has an octahedral truncated spinel structure, while the lithium manganate fired with manganese dioxide has a normal spinel structure. By comparing the crystal forms of lithium manganate, it is shown that after the treatment of EMD, the crystal form of the prepared lithium manganate will change, corresponding to the change in its electrical properties.

[0065] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For parts not detailed or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0066] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and shall all be included in the protection scope of the present application.

Claims

1. A method for preparing lithium manganate after EMD modification and impurity reduction, characterized in that: The following steps are involved: S1, pretreatment: washing the EMD semi-finished product with hot water, drying it, grinding it, and grading it to obtain EMD fine powder; S2, calcining: calcining the EMD fine powder into manganese trioxide, washing and drying after cooling to obtain reduced-doped manganese trioxide; S3, preparation: the EMD fine powder, the reduced-doped manganese trioxide, lithium salt and metal oxide are mixed, ground and sintered to obtain lithium manganate.

2. The method according to claim 1, characterized in that The process conditions of hot water acid washing described in S1 are: temperature of 60°C-100°C, washing time of 20min-1h, and cyclic washing for 2-3 times. The grinding described in S1 is ball milling, and the particle size distribution requirements of the EMD fine powder are: D10=1.5-5μm, D50=8-15μm, D90=20-35μm.

3. The method according to claim 1, characterized in that The process conditions for sintering into manganese trioxide described in S2 are: firing in a roller kiln, the calcination temperature is 600° C.-900° C., and the calcination time is 2 h-6 h.

4. The method according to claim 1, characterized in that: The washing process conditions described in S2 are: washing 2 to 5 times with pure water at a solid-liquid ratio of 1:2 to 4, and the washing time is 20 minutes to 1 hour.

5. The method according to claim 1, characterized in that The content of each impurity metal ion in the reduced-doped manganese trioxide in S2 is less than 100 ppm, the content of impurity sulfate is less than 0.6%, and the specific surface area of ​​the reduced-doped manganese trioxide is 0.5 m 2 / g-1.5m 2 / g.

6. The method according to claim 5, characterized in that The impurity metal ions include at least one of potassium, sodium, calcium and magnesium.

7. The method according to claim 1, characterized in that The lithium salt in S3 is a combination of one or more of lithium carbonate and lithium hydroxide.

8. The method according to claim 1, characterized in that The metal oxide in S3 is a combination of one or more of Al2O3, TiO2, MgO, La2O3, and ZrO2.

9. The method according to claim 1, characterized in that: The molar ratio of the EMD fine powder, the reduced-doped manganese trioxide and the Mn:Li atomic ratio in the lithium salt is (1.6-2):1; the amount of metal oxide added is 0.1%-1% of the total mass of the manganese source and the lithium salt.

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